Accession Number : AD0768356

Title :   Optimal Truncated-Power-Series Approach for Different Reentry Phases.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OHIO SCHOOL OF ENGINEERING

Personal Author(s) : Hollister,Phillip C.

Report Date : JUN 1973

Pagination or Media Count : 86

Abstract : The optimal reentry problem is formulated for a phase by phase planar trajectory. The reentry portion of the trajectory for a shuttle type vehicle is divided into two phases and each phase is treated as an individual optimal control problem. Optimization is with respect to (1) peak heat rate for the entry phase, (2) a combination of total control energy, total heat absorbed, and satisfactory end conditions for the glide phase, and (3) a total surface distance. The control for each phase consists of a truncated power series as a function of the system states and the independent variable range. The entry phase ends at pullup and has a single constant for control. The glide phase ends at conditions desired for a transition from a high to a low angle of attack, the transition phase is left for a later study. By process of elimination the glide phase control form is reduced to a constant plus two terms. Searching for the coefficients which optimize the power series is accomplished using Davidon's minimization routine. Results indicated that a constant adaptive controller is a reasonable sub-optimal solution for both phases. (Modified author abstract)

Descriptors :   (*ATMOSPHERE ENTRY, ADAPTIVE CONTROL SYSTEMS), (*RENDEZVOUS SPACECRAFT, *SPACE NAVIGATION), MANNED SPACECRAFT, DESCENT TRAJECTORIES, ORBITS, POWER SERIES, AERODYNAMIC HEATING, MATHEMATICAL MODELS, THESES

Subject Categories : Spacecraft Trajectories and Reentry

Distribution Statement : APPROVED FOR PUBLIC RELEASE